Excess current switch

ABSTRACT

An excess current switch has a thermal and/or electromagnetic trip, a pivotally mounted actuating member, a bell crank connecting the actuating member with a movable contact carrier and a locking lever for locking the bell crank in an extended position to establish a switched on position of the switch. The switch is further provided with a spring biased latch having a retaining portion which during switch on engages a stop prior to the contact carrier reaching its switched on position. The latch is subsequently disengaged from the stop by an arm of the actuating member to allow the contact carrier to move to its switched on position. When a thermal and/or electromagnetic trip occurs a release lever actuates the locking lever to move it to a release position to thereby allow the bell crank to assume its switched off position and thus allow the switch to break. Such a switch provides for instantaneous switch on and off which results in a lengthening of the life of the contacts of the switch.

6 A United States Patent 1 [111 3,733,239

Ellenberger 1 May 1, 1973 [54] EXCESS CURRENT SWITCH [75] Inventor: Jakob Ellenberger, Altdorf near gummy gi g g i Broome NuembergGermany ttorney- 1c ar s eier [73] Assignee: Ellenberger 8: Poensgen Gmbll, Alt- {57 1 ABSTRACT dorf near Nuemberg Germany An excess current switch has a thermal and/or elec- [22] Filed: June 23, 1972 tromagnetic trip, a pivotally mounted actuating member, a bell crank connecting the actuating [21] Appl' 265311 member with a movable contact carrier and a locking lever for locking the bell crank in an extended posi- [30] Foreign Application Priority Data tion to establish a switched on position of the switch. The switch is further provided with a spring biased July 1, Germany latch having a retaining portion during switch on engages a stop prior to the contact carrier reaching [52] U.S. Cl ..335/167, 335/22 its Switched on position The latch is Subsequently [51] hit. Cl. g g from the p y an arm f the actuating [58] Field of Search ..337/66; 335/168, member to allow the Contact carrier to move to its 335/16716917017217422 switched on position. When a thermal and/0r electromagnetic trip occurs a release lever actuates the 1 References Cited locking lever to move it to a release position to thereby allow the bell crank to assume its switched off UNITED STATES PATENTS position and thus allow the switch to break. Such a 1,701,440 2/1929 Chatto ..335/l68 switch provides for instantaneous switch on and off 2,795,670 6/1957 Cellerini et ......335/22 which results in a lengthening of the life of the con- 3,l03,565 9/1963 Walker et al.... ...335/22 {a t of the switch, 3,663,903 5/1972 Kussy et al. ...335/l6 3,657,672 4/1972 Flick et al ..335/ 168 7 Claims, 3 Drawing Figures PATENTED HAY 1 SHEET 2 BF 3 PATENTEU 1 1973 3. 731 .239

SHEET 3 [IF 3 EXCESS ctJnRENT switch The invention relates to an excess current switch, and more especially to a single-pole or multi-pole excess current switch having a thermal and/or electromagnetic trip, a pivotally mounted actuating member connected, by means of a bell-crank, to a pivotally contact carrier.

An excess current switch of this kind is disclosed in German Offenlegungsschrift No. 1,563,781 which, although it has the advantage of having relatively few, lightweight structural components to allow for rapid tripping it does suffer from the drawback of not allow ing instantaneous switching on. As a result, arcs can form during switching on which prematurely destroy the contact elements and which can shorten the life of the entire excess current switch.

The present invention is concerned with providing an excess current switch in which switching on and off proceeds as rapidly as possible so that the contact elements are preserved in good condition and therefore a high performance and a long working life of the switch are obtained.

According to the invention there is provided a single or multi-pole excess current switch having a thermal and/or electromagnetic trip, such a switch comprising a pivotally mounted manual actuating member having first and second arms, a bell crank having a first lever connected to the first arm of the actuating member and a second lever connected to a pivotally mounted contact carrier for a movable contact of the switch, a first spring for urging the first lever of the bell crank away from the first arm of the actuating member, a locking lever pivotally mounted on one of the levers of the bell crank, a further spring adapted to bias the locking lever to a locking position in which it engages the other of the levers of the bell crank to lock the bell crank in an extended position thereof, a release lever adapted to be actuated by the thermal and/or electromagnetic trip to move the locking lever to a release position, and a spring biased latch pivotally mounted on the contact carrier, the latch having a retaining portion which during switching on firstly engages a stop prior to the contact carrier reaching its switched on position to overcome the spring bias of the latch and which is subsequently disengaged from the stop by the first arm of the actuating member to allow the contact carrier to move to its switched on position.

In the switched on position of the excess current switch the extended bell crank is locked by the locking lever. When an excess current occurs the lever actuatable by the thermal and/or electromagnetic trip swings the locking lever into its release position so that the extended bell crank rapidly assumes a folded configuration to move the contact carrier to its switch off position. This switching off is instantaneous to thereby protect the contact elements of the switch. The release also occurs when the actuating member is retained in the connecting position during tripping (trip-free release).

Since in the switched on position the bell crank is locked in its extended position by the locking lever the entire, locked, bell crank together with the first arm of the actuating member form a further bell crank. When switching off manually, the extended and locked bell crank is pivoted by the actuating member. When the dead center of the bell crank formed by the first arm of the actuating member and the extended bell crank is surpassed, the spring acting on the latch becomes immediately effective, and causes the separation of the contact elements.

When one proceeds from this switched off position to the switched on position, then the contact elements do not contact one another since prior to this connected position the retaining portion of the latch engages the stop which is preferably integral with a housing for the switch whereby the switching on movement of the movable contact element is interrupted. Only when, in the final phase of the switching on movement of the actuating member does the first arm thereof impinge on the latch and effect disengagement of the latter from the stop to cause a jerky pivoting of the contact carrier under the action of the spring which tends to urge the first lever of the bell crank away from the first arm of the actuating member. Thereby the movable contact element is also jerkily brought into contact with the fixed contact member of the switch. The

present excess current switch can, therefore, be advantageously employed as a heavy duty switch. This advantage of instantaneous switching on of the present excess current switch is not provided in the excess current switch disclosed in German Offenlegungsschrift No. 1,563,781.

In order to obtain simple locking of the bell crank in the extended position by the locking lever, the first lever of the bell crank may include an end portion which extends beyond its axis of rotation, the locking lever being pivotally mounted on the said end portion.

To enable the bell crank to automatically assume its extended position and to enable the locking lever to arrive in its release position during the switching off movement of the actuating member, a torsion spring is provided. This torsion spring is pivotally mounted about an axis which is common to the pivotal axis of the locking lever, one arm of the torsion spring bearing against the locking lever and the other arm thereof bearing against the first lever of the bell crank.

In one form the present switch includes a contact arm carrying the movable contact pivotally mounted about an axis which is common to the pivotal axis of the latch and a spring adapted to bias the movable contact via the contact arm toward a fixed contact in the switched on position of the switch, the contact arm being adapted to engage a shaft on which the contact carrier is pivotally mounted in the switched off position of the switch. Upon thermal or electromagnetic tripping this spring effecting the contact pressure contributes to the breaking of the bell crank and thus assists in the rapid tripping of the switch.

Further the switch may include a lever adapted to be pivoted by the armature of the electromagnetic trip to engage the contact arm. In the event of a short circuit, in particular, an extremely rapid, current-limiting disconnection is achieved with this arrangement.

In a preferred form the actuating member includes a projection for disengaging the retaining portion of the latch from the stop, the said projection being arranged adjacent the point of connection between the first arm of the actuation member and the first lever of the bell crank.

In addition the switch may include a further stop arranged in the path of movement of the locking lever to cause the locking lever to disengage from the said other lever of the bell crank during a manual switching off operation.

An illustrative embodiment of the invention will now be described with reference to the accompanying drawings, in which:

FIG. 1 illustrates the switching mechanism of one form of an excess current switch, in switched on position;

FIG. 2 illustrates the switching mechanism shown in FIG. 1 in the switched off position after manual release; and

FIG. 3 illustrates the switching mechanism shown in FIG. 1 after trip-free release.

The switching mechanism shown in the drawings is accommodated in a housing (not shown), from which an actuating member 1 designed as a two-armed lever and two terminals 2 and 3 protrude. The actuating member 1 is pivotally mounted on a shaft 4 arranged within the housing. A tension spring 6 is connected to an arm of the actuating member 1. The arm 5 has an elongate slot 7 into which engages a shaft 8 of a lever 9. In the arm 5 there is a spring 10 which engages a member which is attached to one end of the lever 9. The lever 9 is connected to a lever 13 by means of a shaft 12. The two levers 9 and 13 form a bell crank. The lever 13 is made from sheet metal member bent to form a U shape. In the drawings only one leg thereof together with the transverse portion 14 illustrated in section is visible. The lever 9 extends beyond the shaft 12 and is connected, by means of a shaft 15, to a locking lever 16 which has a retaining portion 17 which engages behind the transverse portion 14 of the lever 13. In the switched on position as shown in FIG. 1 the locking lever 16 locks both levers 9 and 13 of the bell crank in their almost fully extended positions so that they form a rigid structure in this locked position. A spring 18 designed as a torsion spring and disposed on the shaft has an arm which bears on the lever 9 and another arm supported in a bore 19 of the locking lever 16 to maintain the locking lever 16 in its locked position as shown in FIG. 1. In this locked position the rigid bell crank forms a bell crank with the arm 5 of the actuating member 1.

The lever 13 is connected with a contact carrier 21 by means of a pin 20, the contact carrier 21 being pivotably mounted in the housing by means of a shaft 22. The contact carrier 21 is made from sheet metal and is bent to a U shape. A pin 23 is provided to pivotably mount a contact arm 24 in the contact carrier 21. With the aid of the pin 23 a latch 25 is connected with the contact carrier 21, the latch 25 having a retaining portion 26 and an angular recess 27. One end of the latch 25 engages a tension spring 28 which has one end thereof attached to a pin 29 disposed in the housing. The said one end of the latch 25 cooperates with a projection 30 of the arm 5 of the actuating member 1. Interiorly of the contact carrier 21 there is a spring 31 one end of which engages against the contact arm 24 and the other end against the transverse portion of the contact carrier 21. As shown in FIG. 1 a contact element 32 of the contact arm 24 engages a fixed contact element 33 of the terminal 3 under the action of the spring 31. The spring 31 also provides the contact pressure. The contact arm 24 has an attachment 34 with which the contact arm 24 engages in the switched off position shown in FIGS. 2 and 3 to the shaft 22 under the action of the spring 31.

The contact arm 24 is connected by a stranded wire 35 to one end of a coil 36 of an electromagnet 37, the other end of which is connected by a stranded wire 38 to a bimetal strip 39 secured to the terminal 2. The bimetal strip 39 has a setting screw 40 capable of acting on a lever 41 of angular form when the bimetal strip 39 is bowed. The lever 41 is pivotably mounted by means of a shaft 42 arranged in the housing. A compression spring 43 acts on the lower arm of the lever 41. The lever 41 can swing the locking lever 16 into its inactive position with its upper arm.

The electromagnet 37 has an armature 44 provided with a setting screw 45 at its left end which screw acts on the lower arm of the lever 41 when the armature 44 is attracted by the energized electromagnet 37.

The armature 44 of the electromagnet 37 also has an abutment 46 capable of cooperating with an angularly shaped lever 47 pivotably mounted in the housing by means of a shaft 48. When this lever 47 is pivoted in anti-clockwise direction the end 49 of the lever 47 impinges on the contact arm 24 and jerkily lifts its contact element 32 off the fixed contact element 33. Opening of the contacts is thereby accelerated and, especially upon short circuiting, a current limiting effect is obtained.

In the switched on position as shown in FIG. 1 the current flows from the terminal 2 through the bimetal strip 39, the wire strand 38, the coil 36, the wire strand 35, the contact arm 24, contact elements 32 and 33 to the terminal 3. When an excess current develops the bimetal strip 39 is bowed in anti-clockwise direction, its setting screw 41 acting on the lower arm of the lever 41 and pivoting the latter in anti-clockwise direction so that its upper arm swings the latch 16 in clockwise direction into its release position in which its retaining portion 17 no longer engages the transverse portion 14 of the lever 13. Under the action of the spring 31 and particularly the spring 28 the bell crank comprising the two levers 9 and 13 contracts, whereby the movable contact element 32 is lifted off the fixed contact element 33 and thereby the current is interrupted. The same effect is obtained when, upon electromagnetic trip, the armature 44 acts with its setting screw 45 on the lower arm of the lever 41. In the event of short circuit actuation of the angular lever 47 by the abutment 46 of the armature 44 swings the contact arm 24 extremely rapidly in anti-clockwise direction and thus its mobile contact element 32 is lifted off the fixed contact element 33.

The above described tripping action takes place independently of the position of the actuating member 1. If the actuating member 1 is retained in its switching on position as shown in FIG. 1, trip-free release will occur, whereafter the switch mechanism will assume the position illustrated in FIG. 3. By providing a freely movable actuating member 1, the actuating member will during release be pivoted in anti-clockwise direction into the switching off position, by the tension spring 6. The switch mechanism then assumes the position illustrated in FIG. 2 wherein the locking lever locks the bell crank comprising the two levers 9 and 13 in its extended position.

When switching on takes place from the FIG. 2 position of the switch mechanism, the actuating member 1 has to be pivoted in clockwise direction, then the contact carrier 21, and thus also the contact arm 24, is pivoted in clockwise direction about the shaft 22 via the almost straight bell crank locked by the locking lever 16. During this movement the latch is entrained by the contact carrier 21 and moved downwardly as shown in FIG. 2, whereby the spring 23 is tensioned. This movement continues until the retaining portion 26 of the latch 25 meets a stop 50 integral with the housing. The movable contact element 32 of the contact arm 24 is now slightly above the fixed contact element 33, i.e. not yet in the switching on position. Impinging of the retaining portion 26 of the latch 25 on the stop 50 integral with the housing occurs prior to the bell crank formed by the arm 5 of the actuating member l and the almost extended and locked bell crank reaching its dead center position. Until the bell crank reaches the dead center position the spring 10 is compressed by the axis 8 of the lever 9. In so doing the axis 8 moves in the elongate slot 7 of the arm 5 toward the axis 4 of the actuating member 1. After passing the dead center position the proturberance 30 of the arm 5 of the actuating member 1 meets the said one end of the latch 25 and swings the latter in anti-clockwise direction until its retaining portion 26 disengages from the stop 50 integral with the housing. Under the action of the tensioned spring 10 the contact carrier 21 is now pivoted, in clockwise direction, about its shaft 22 via the almost extended and locked bell crank, and thus the contact arm 24 with its movable contact element 32 is jerked into contacting relationship with the fixed contact element 33, whereby instantaneous switching on is obtained.

In the switched on position illustrated in FIG. 1 the latch 25 contacts in the region of its angular recess 27 the stop 50 integral with the housing, under the action of the spring 28. 7

Within the area defined by the locking lever 16 there may be present in the housing of the illustrated excess current switch a stop onto which the locking lever 16 impinges when switching off manually and by which stop the lever 16 is caused to disengage from the transverse portion 14 acting as projection, so that the bell crank can collapse and rapid release becomes possible also when switching off manually. For this purpose the locking lever may have an additional arm cooperating with the not illustrated stop integral with the housing.

In FIG. 1 the excess current switch is shown as a single-pole switch. Several such single-pole excess current switches may be arranged side-by-side and connected to form a multi-pole excess current switch.

I claim:

1. A single or multi-pole excess current switch having a thermal and/or electromagnetic trip, such a switch comprising a pivotally mounted manual actuating member, said actuating member having first and second arms, a bell crank, said bell crank having first and second levers, said first lever being connected to the first arm of the actuating member, a pivotally mounted contact carrier, said second lever being connected to the pivotally mounted contact carrier a first spring, said first spring being adapted to urge the first lever of the bell crank away from the first arm of the actuating member, a locking lever, said locking lever being pivotally mounted on one of said levers of the bell crank, a further spring, said further spring being adapted to bias the locking lever to a locking position in which it engages the other of the levers of the bell crank to lock the bell crank in an extended position. thereof, a release lever, said release lever being adapted to be actuated by the thermal and/or electromagnetic trip to move the locking lever to a release position, a spring biased latch, said latch being pivotally mounted on the contact carrier, the latch having a retaining portion, and a stop, said retaining portion during switching on being adapted firstly to engage said stop prior to the contact carrier reaching its switched on position to overcome the spring bias of the latch and subsequently to be disengaged from the stop by the first arm of the actuating member to allow the contact carrier to move to its switched on position.

2. A switch according to claim 1 in which the first lever of the bell crank includes an end portion, the said end portion extending beyond its axis of rotation, the locking lever being pivotally mounted on the said end portion.

3. A switch according to claim 1 which includes a torsion spring, said torsion spring being pivotally mounted about an axis which is common to the pivotal axis of the locking lever, one arm of the torsion spring bearing against the locking lever and the other arm thereof bearing against the first lever of the bell crank.

4. A switch according to claim 1 which includes a contact arm, said contact arm carrying the movable contact of the switch and being pivotally mounted about an axis which is common to the pivotal axis of the latch and a spring, said spring being adapted to bias the movable contact via the contact arm toward a fixed contact in the switched on position of the switch, the contact arm being adapted to engage a shaft on which the contact carrier is pivotally mounted in the switched off position of the switch.

5. A switch according to claim 4 which includes a lever, said lever being adapted to be pivoted by the armature of the electromagnetic trip to engage the contact arm.

6. A switch according to claim 1 in which the actuating member includes a projection, said projection being adapted to disengage the retaining portion of the latch from the stop, the said projection being arranged adjacent the point of connection between the first arm of the actuation member and the first lever of the bell crank.

7. A switch according to claim 1 which includes a further stop, said further stop being arranged in the path of movement of the locking lever to cause the locking lever to disengage from the said other lever of the bell crank during a manual switching off operation. 

1. A single or multi-pole excess current switch having a thermal and/or electromagnetic trip, such a switch comprising a pivotally mounted manual actuating member, said actuating member having first and second arms, a bell crank, said bell crank having first and second levers, said first lever being connected to the first arm of the actuating member, a pivotally mounted contact carrier, said second lever being connected to the pivotally mounted contact carrier, a first spring, said first spring being adapted to urge the first lever of the bell crank away from the first arm of the actuating member, a locking lever, said locking lever being pivotally mounted on one of said levers of the bell crank, a further spring, said further spring being adapted to bias the locking lever to a locking position in which it engages the other of the levers of the bell crank to lock the bell crank in an extended position thereof, a release lever, said release lever being adapted to be actuated by the thermal and/or electromagnetic trip to move the locking lever to a release position, a spring biased latch, said latch being pivotally mounted on the contact carrier, the latch having a retaining portion, and a stop, said retaining portion during switching on being adapted firstly to engage said stop prior to the contact carrier reaching its switched on position to overcome the spring bias of the latch and subsequently to be disengaged from the stop by the first arm of the actuating member to allow the contact carrier to move to its switched on position.
 2. A switch according to claim 1 in which the first lever of the bell crank includes an end portion, the said end portion extending beyond its axis of rotation, the locking lever being pivotally mounted on the said end portion.
 3. A switch according to claim 1 which includes a torsion spring, said torsion spring being pivotally mounted about an axis which is common to the pivotal axis of the locking lever, one arm of the torsion spring bearing against the locking lever and the other arm thereof bearing against the first lever of the bell crank.
 4. A switch according to claim 1 which includes a contact arm, Said contact arm carrying the movable contact of the switch and being pivotally mounted about an axis which is common to the pivotal axis of the latch and a spring, said spring being adapted to bias the movable contact via the contact arm toward a fixed contact in the switched on position of the switch, the contact arm being adapted to engage a shaft on which the contact carrier is pivotally mounted in the switched off position of the switch.
 5. A switch according to claim 4 which includes a lever, said lever being adapted to be pivoted by the armature of the electromagnetic trip to engage the contact arm.
 6. A switch according to claim 1 in which the actuating member includes a projection, said projection being adapted to disengage the retaining portion of the latch from the stop, the said projection being arranged adjacent the point of connection between the first arm of the actuation member and the first lever of the bell crank.
 7. A switch according to claim 1 which includes a further stop, said further stop being arranged in the path of movement of the locking lever to cause the locking lever to disengage from the said other lever of the bell crank during a manual switching off operation. 